Reopen PDFs from last session option greyed out

[RC87]

I can't seem to select the "Open PDF's from last session on Acrobat launch" option (screenshot below). The option is always greyed out for me. Please advise on how to fix this as it seems rather archaic to have to open all of the PDFs I previously had open each time my computer or Adobe restarts. 

I am running Windows 10 and have Adobe Acrobat Pro 2020. 

[Bernd Alheit · Accepted solution]

Enable the option below this option.

[RC87]

Is there any other way? Working with tabs doesn't suit my workflow. 

[Bernd Alheit]

There is no other way to activate the option.